HE 441 was a short cruise (8 days) by scientists and students of Bremen University, MARUM, BAW in the framework of the research projects MARUM SD1/CCP5, NOAH, and COSYNA. Because of technical problems (sewage system), a sick chief, and severe weather constraints (storm Niklas) the cruise was interrupted and considerably shorter than planned.

Three locations in the southern German Bight were visited for intense observations of physical processes in the water column and on the sea floor. These locations had been defined as representative sedimentary focus areas in the research project NOAH beforehand. At each of the locations NOAH A, NOAH D, and NOAH E a combination of ship based measurements, water column profiling, and the deployment of autonomous observatories (lander) was carried out. The bathymetry and sedimentology of each of these domains was characterized by multi-beam echo sounder and sediment grab samples before deployment of two autonomous landers equipped with different sensors and instruments for sea bed sediment dynamics and hydrodynamics. Also upward looking ADCP in trawl-resistant bottom frames (TRBM) were deployed.

These landers remained on the sea floor for several tidal cycles at each locations. In the vicinity of the lander positions the ship was anchored and water column properties were measured by ship based ADCP, CTD profiling, and the deployment of a combined sensor frame for particle size and hydrodynamics at specified depths. Changing wind and weather conditions allowed the observation of different boundary conditions to the seafloor at each location. Preliminary data analyses reveal the different characteristics of seafloor morphodynamics (existence and migration of small scale bedforms), sediment dynamics (erosion and suspension of sediments in reaction to the hydrodynamic forcing in timescales of waves and tidal currents), and water column hydrodynamics and turbulence properties. At the locations no pronounced stratification of the water column could be observed, however water column properties (hydrodynamics, turbidity, particle size) varied considerably throughout the tidal cycles.

RV Heincke

A benthic Lander for autonomous observations of the seafloor dynamics.